US6570364B2 - Circuit and method for monitoring the operational reliability of rechargeable lithium cells - Google Patents

Circuit and method for monitoring the operational reliability of rechargeable lithium cells Download PDF

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Publication number
US6570364B2
US6570364B2 US10/056,854 US5685402A US6570364B2 US 6570364 B2 US6570364 B2 US 6570364B2 US 5685402 A US5685402 A US 5685402A US 6570364 B2 US6570364 B2 US 6570364B2
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cell
voltage
threshold value
limit
predetermined
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Expired - Lifetime
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US10/056,854
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US20020105304A1 (en
Inventor
Rainer Haid
Peter Birke
Konrad Holl
Dejan Ilic
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VARTA Microbattery GmbH
VW Kraftwerk GmbH
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Microbatterie GmbH
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Publication of US20020105304A1 publication Critical patent/US20020105304A1/en
Assigned to VARTA MICROBATTERIE GMBH, A CORPORATION OF GERMAND reassignment VARTA MICROBATTERIE GMBH, A CORPORATION OF GERMAND CHANGE OF NAME (SEE DOCUMENT FOR DETAILS). Assignors: MICROBATTERIE GMBH
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Publication of US6570364B2 publication Critical patent/US6570364B2/en
Assigned to VARTA MICROBATTERY GMBH, A CORPORATION OF GERMANY reassignment VARTA MICROBATTERY GMBH, A CORPORATION OF GERMANY CORRECTED COVER SHEET TO CORRECT ASSIGNEE NAME, PREVIOUSLY RECORDED AT REEL/FRAME 014098/0510 (CHANGE OF NAME) Assignors: MICROBATTERIE GMBH
Assigned to VOLKSWAGEN VARTA MICROBATTERY FORSCHUNGSGESELLSCHAFT MBH & CO KG reassignment VOLKSWAGEN VARTA MICROBATTERY FORSCHUNGSGESELLSCHAFT MBH & CO KG ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: VARTA MICROBATTERY GMBH
Assigned to VW-VM FORSCHUNGSGESELLSCHAFT MBH & CO. KG. reassignment VW-VM FORSCHUNGSGESELLSCHAFT MBH & CO. KG. CHANGE OF NAME (SEE DOCUMENT FOR DETAILS). Assignors: VOLKSWAGEN VARTA MICROBATTERY FORSCHUNGSGESELLSCHAFT MBH & CO. KG
Assigned to VW KRAFTWERK GMBH (25%), VARTA MICROBATTERY GMBH (75%) reassignment VW KRAFTWERK GMBH (25%) ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: VARTA MICROBATTERY GMBH (50%), VW-VM FORSCHUNGSGESELLSCHAFT MBH & CO. KG (50%)
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values
    • G01R19/16533—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values characterised by the application
    • G01R19/16538—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values characterised by the application in AC or DC supplies
    • G01R19/16542—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values characterised by the application in AC or DC supplies for batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/44—Methods for charging or discharging
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/374—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC] with means for correcting the measurement for temperature or ageing
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

A method for monitoring the operational reliability of rechargeable lithium cells including measuring the cell voltage and cell temperature, the cell is discharged if a predetermined cell limit voltage (UG) and a predetermined ambient limit temperature TG are exceeded at the same time, until a predetermined lower voltage level or a predetermined lower ambient temperature is reached. A circuit for carrying out the method has a first threshold value switch which responds when a predetermined upper limit voltage (UG) is exceeded in the cell, and a second threshold value switch (C) which responds when a predetermined ambient temperature limit (TG) is exceeded, and has a logic circuit (E) which connects (G) the cell to a load when the first and second threshold value switches respond at the same time, wherein both threshold value switches (C, D) are configured such that they trip when a lower cell voltage or a lower ambient temperature is reached.

Description

FIELD OF THE INVENTION
The invention relates to a circuit and method for monitoring the operational reliability of rechargeable lithium cells, by measuring and monitoring the cell voltage and the cell temperature.
BACKGROUND
Rechargeable lithium/ion cells require a special charging technique and, in particular, predetermined switch-off voltages must be complied with exactly while, if the charger fails, a protective circuit must prevent and inhibit further charging. When such cells are being discharged, specific voltage lower limits must not be infringed, to avoid irreversible damage to the cell. Lithium-ion cells are thus provided with special electronic protective switches which switch off at predetermined final charging and discharge voltages if the charger or the appliance behaves incorrectly and, together with special protection devices, are intended to protect the cell against unacceptable voltage levels and currents, and to prevent dangerous situations occurring, which could result in irreversible decomposition of the electrolyte and cell damage. Chargers with such monitoring functions are described, for example, in WO96/15563.
Thus, it would be advantageous to provide a method which further improves the operational reliability of rechargeable lithium cells.
SUMMARY OF THE INVENTION
This invention relates to a method for monitoring operational reliability of rechargeable lithium cells including measuring cell voltage and cell temperature, and discharging the cell if a predetermined cell limit voltage (UG) and a predetermined ambient limit temperature (TG) are exceeded substantially at the same time, until a predetermined lower voltage level or a predetermined lower ambient temperature is reached.
This invention also relates to a circuit arrangement for carrying out the above method and includes a first threshold value switch (D) connected to respond when a predetermined upper limit voltage (UG) is exceeded in the cell, a second threshold value switch (C) connected to respond when a predetermined ambient temperature limit (TG) is exceeded, and a logic circuit (E) which connects load resistance (G) to a load when the first and second threshold value switches (D) and (C) respond at substantially the same time, and wherein the first and second threshold value switches (C) and (D) are configured such that they trip when a lower cell voltage or a lower ambient temperature is reached.
BRIEF DESCRIPTION OF THE DRAWINGS
The subject matter of the invention will be explained in more detail in the following text with reference to the Figures.
FIG. 1 in this case shows a schematic circuit diagram of a circuit arrangement which is suitable for carrying out the method.
FIG. 2 shows the profile of the cell capacity as a function of the cell voltage during charging CL and discharging CEL during a charging/discharging cycle, which is carried out with a current of C/2.
DETAILED DESCRIPTION
The method according to the invention protects the lithium cell against electrochemical decomposition at high temperature and in critical charge states, while discharging the cell until sufficient capacity is still available that the cell is no longer in a critical charge state or at a critical temperature.
Referring to FIG. 1, the battery voltage UB is used to produce an auxiliary voltage UH in the circuit module A, which is required to ensure correct operation of the threshold value switches and logic gates in the entire circuit. The stable auxiliary voltage UH is preferably considerably less than the minimum battery voltage. The battery voltage in the lithium cells under consideration here is between about 2.7 and about 4.2 volts, so that the stable auxiliary voltage may be, for example, approximately 2.5 volts.
A temperature sensor B produces a voltage signal which is proportional to the ambient temperature, and is supplied to a threshold value switch C. If a predetermined upper limit temperature TG is exceeded, the threshold value switch C changes to the on state. This threshold value switch is configured with hysteresis. It switches back to the off state only when the temperature falls below a new level, which is considerably below the limit temperature TG. A further threshold value switch D switches to the on state when the battery voltage reaches a predetermined upper limit value UG. This threshold value switch is also configured with hysteresis, so that it does not switch back to the off state until a considerable separation is reached between the previously achieved limit voltage UG and the voltage that occurs subsequently.
The output signals from the two threshold value switches C and D are fed to a logic gate, via which the load resistance G is connected by the switch F to the battery when both the temperature and the voltage reach the predetermined limit values. This discharging process is interrupted when either the cell voltage has fallen considerably below the limit voltage UG of the threshold value switch D or the ambient temperature has fallen below the lower switching threshold of the threshold value switch C.
A voltage of approximately 4 volts is preferably chosen as the upper limit voltage. This corresponds to a cell charge state of 90%, and the upper limit temperature TG is defined to be about 80°. The discharging of the cell, which takes place when both limit values are overshot, should be carried out down to a voltage of approximately 3.82 volts, i.e., down to a charge state of 70%. However, it may also be sufficient for the discharging process to allow the voltage to fall only to approximately 3.9 volts, with about 70° C. or about 60° C. being chosen as the lower limit value for the temperature.
The voltage and temperature limit values are determined and defined specifically for each system. In order to define the lower voltage value, the lower limit voltage is chosen such that, at the end of the discharging process, the voltage does not recover above the upper limit value once again, so that it would not be possible for the circuit to oscillate.
Configuring the threshold value switches with hysteresis largely prevents any tendency to oscillate. The functions of the described outline circuit can be incorporated in known IC circuits which are used for monitoring the operation of rechargeable lithium cells.
The measures according to the invention allow rechargeable lithium cells, in particular, lithium polymer cells, to be protected against mechanical and electrochemical damage at high temperatures, as a result of charge states at which secondary electrochemical reactions can occur due to the level of the cell voltage and the level of the ambient temperature, resulting in an increase in the internal resistance and capacity losses.

Claims (8)

What is claimed is:
1. A method for monitoring operational reliability of a rechargeable lithium cell comprising:
measuring cell voltage and cell temperature; and
discharging the cell if a predetermined cell limit voltage (UG) and a predetermined ambient limit temperature (TG) are exceeded substantially at the same time, until a predetermined lower voltage level or a predetermined lower ambient temperature is reached.
2. The method as claimed in claim 1, wherein the limit voltage (UG) is about 4.0 volts, and the limit temperature (TG) is approximately 80° C.
3. The method as claimed in claim 1, wherein the lower voltage level is less than about 3.9 volts, and the lower ambient temperature limit is about 70° C.
4. The method as claimed in claim 2, wherein the lower voltage level is less than about 3.9 volts, and the lower ambient temperature limit is about 70° C.
5. The method as claimed in claim 1, wherein the lower limit voltage is about 3.82 volts, and the lower limit temperature is about 60° C.
6. The method as claimed in claim 2, wherein the lower limit voltage is about 3.82 volts, and the lower limit temperature is about 60° C.
7. A circuit for carrying out the method as claimed in claim 1 comprising:
a first threshold value switch (D) connected to respond when a predetermined upper limit voltage (UG) is exceeded in the cell;
a second threshold value switch (C) connected to respond when a predetermined ambient temperature limit (TG) is exceeded; and
a logic circuit (E) which connects load resistance (G) to a load when the first and second threshold value switches (D) and (C) respond at substantially the same time, and wherein the first and second threshold value switches (C) and (D) are configured such that they trip when a lower cell voltage or a lower ambient temperature is reached.
8. A circuit arrangement for monitoring operational reliability of a rechargeable lithium cell comprising:
a first threshold value switch (D) connected to respond when a predetermined upper limit voltage (UG) is exceeded in the cell;
a second threshold value switch (C) connected to respond when a predetermined ambient temperature limit (TG) is exceeded; and
a logic circuit (E) which connects load resistance (G) to a load when the first and second threshold value switches (D) and (C) respond at substantially the same time, and wherein the first and second threshold value switches (C) and (D) are configured such that they trip when a lower cell voltage or a lower ambient temperature is reached.
US10/056,854 2001-02-03 2002-01-25 Circuit and method for monitoring the operational reliability of rechargeable lithium cells Expired - Lifetime US6570364B2 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE10104981A DE10104981A1 (en) 2001-02-03 2001-02-03 Procedure for monitoring the operational safety of rechargeable Li cells
DEDE10104981.1 2001-02-03
DE10104981 2001-02-03

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US20020105304A1 US20020105304A1 (en) 2002-08-08
US6570364B2 true US6570364B2 (en) 2003-05-27

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US (1) US6570364B2 (en)
EP (1) EP1229339B1 (en)
JP (1) JP4353671B2 (en)
KR (1) KR100881817B1 (en)
CN (1) CN1221056C (en)
AT (1) ATE490473T1 (en)
DE (2) DE10104981A1 (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20170264105A1 (en) * 2016-03-08 2017-09-14 Lucas STURNFIELD Method and apparatus for electric battery temperature maintenance
US10336209B2 (en) * 2014-01-22 2019-07-02 Robert Bosch Gmbh Method and device for operating a battery, in particular a lithium ion battery, in a consumer
US10615400B2 (en) 2013-05-08 2020-04-07 Vw Kraftwerk Gmbh Battery with a safety device which can be reset, and also suitable pole stud for the battery

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US20070257642A1 (en) * 2003-06-19 2007-11-08 Sean Xiao Battery cell monitoring and balancing circuit
US7081737B2 (en) * 2003-06-19 2006-07-25 O2Micro International Limited Battery cell monitoring and balancing circuit
DE10361360A1 (en) * 2003-12-18 2005-07-14 Varta Microbattery Gmbh Galvanic element
DE102007031557A1 (en) 2007-07-06 2009-01-08 Robert Bosch Gmbh Accumulator with internal unloading device
US8872478B2 (en) * 2010-03-09 2014-10-28 O2Micro Inc. Circuit and method for balancing battery cells
JP5794104B2 (en) * 2011-10-27 2015-10-14 ソニー株式会社 Battery pack, power storage system, electronic device, electric vehicle and power system
DE102011089700A1 (en) 2011-12-22 2013-06-27 Volkswagen Varta Microbattery Forschungsgesellschaft Mbh & Co. Kg Battery e.g. lithium ion battery for e.g. notebook computer, has pneumatically actuated electrical switches that are operated to alter circuitry state when pressure within housing is above threshold value, and trigger safety mechanism
DE102012213100B4 (en) 2012-07-25 2015-08-06 Volkswagen Varta Microbattery Forschungsgesellschaft Mbh & Co. Kg Battery with thermal switch and pneumatically actuated switch and method for safe operation of the battery
DE102015207043A1 (en) 2015-04-17 2016-11-17 Varta Microbattery Gmbh Battery with pneumo-electric safety switch
KR20220045450A (en) * 2020-10-05 2022-04-12 주식회사 엘지에너지솔루션 Apparatus for Managing Swelling of Secondary Battery and Method of Controlling the Same

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Cited By (3)

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Publication number Priority date Publication date Assignee Title
US10615400B2 (en) 2013-05-08 2020-04-07 Vw Kraftwerk Gmbh Battery with a safety device which can be reset, and also suitable pole stud for the battery
US10336209B2 (en) * 2014-01-22 2019-07-02 Robert Bosch Gmbh Method and device for operating a battery, in particular a lithium ion battery, in a consumer
US20170264105A1 (en) * 2016-03-08 2017-09-14 Lucas STURNFIELD Method and apparatus for electric battery temperature maintenance

Also Published As

Publication number Publication date
ATE490473T1 (en) 2010-12-15
DE10104981A1 (en) 2002-08-08
EP1229339A2 (en) 2002-08-07
DE50214793D1 (en) 2011-01-13
KR100881817B1 (en) 2009-02-03
CN1379499A (en) 2002-11-13
EP1229339A3 (en) 2003-06-18
EP1229339B1 (en) 2010-12-01
CN1221056C (en) 2005-09-28
US20020105304A1 (en) 2002-08-08
JP4353671B2 (en) 2009-10-28
KR20020064866A (en) 2002-08-10
JP2002289264A (en) 2002-10-04

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